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Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
RESEARCH ARTICLE

The chemical and photochemical properties of some 1,3-Diphenyl-2-pyrazolines

NA Evans, DE Rivett and JFK Wilshire

Australian Journal of Chemistry 27(10) 2267 - 2274
Published: 1974

Abstract

The effect of solvent and structure on the stability to light of a series of 1,3-diphenyl-2-pyrazolines has been studied. The major photochemical reaction observed is dehydrogenation to the corresponding 1,3-diphenylpyrazole unless the 5-position is disubstituted when, as in the case of 1,3,5,5-tetraphenyl-2- pyrazoline, photo-oxidation, with either retention or destruction of the heterocyclic ring, occurs. Evidence is presented that singlet oxygen may be involved in the photodehydrogenation of 1,3- diphenyl-2-pyrazoline. The observation that the presence of bulky groups in both the 4- and 5-positions improved both the fluorescence efficiency and the stability to light of the 1,3-diphenyl-2-pyrazoline molecule may have significance for the design of pyrazoline whitening agents. Dehydrogenation of the same series of pyrazolines with chloranil has been studied in order to determine the effect of substituents on the yield of pyrazole.

https://doi.org/10.1071/CH9742267

© CSIRO 1974

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